Improvement in slide-valves of steam-engines



UNTTED STATES PATENT OEEIcE.

JOHN F. ALLEN, OF NEIV YORK, N. Y.

Specification forming part of Letters Patent No. 35,069, dated April 29, 1862.

T0 @ZZ whom it may concern.-

Be it known that I, JOHN F. ALLEN, of the city of New York, in the county and State of New 4York, have in vented a certain new and useful Improvement in Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had tothe accompanying drawings, and to the letters of reference marked thereon.

My invention relates to a modification of the form and mode of operation of the valves of steam engines, relating particularly to slide-valves employed either for the admission or the release of steam to or from the steamcylinder, in contradistinction to those valves which perform the double oiiice of admission and release.

In steam-engines it is desirable to uncover and also to close a large area of steam port or passage by a slight movement of the valve, especially at that part of its movement where it is commencing to uncover or completing the close of the port or passage, whereby in the case of admitting and cutting* off steam the wasteful effects of wire-drawing are in a great measure avoided, and in exhausting speedy release is attained. It is also desirable that the passage from the valve to the cylinder should be short and of simple form.

In view of these considerations my said invention consists in the employment of a slidevalve having in it one or more cavities or passages open only on the face of the valve, in combination with a seat formed substantially in the manner hereinafter set forth, when the said valve and its seat are so arranged relatively to eachother that con'iniunieation may be opened to one end of the steam-cylinder both by the uncovering of the steamwpassage by the end of the valve, and also at the same time through the aforesaid cavity formed in the valve,as is hereinafter set forth.

To enable others skilled in the art to make and use my invention, I will proceed toa description thereof.

In the annexed drawings, forming part of this specification, Figure I represents a vertical section of the upper portion of one end of a steam-cylinder, its steam-chest, and a steamvalve with its seat, illustrating my improvement. Fig. 2 is a similar view oil the same parts, showing the steam-valve wide open.

Fig. 3 shows a plan view of the underside of the valve; and Fig. 4c represents a horizontal section of one end of the steam-chest, showing the valveseat.

Similar letters of reference denote the same parts in the several aforesaid figures, to which figures the immediately following description refers.

A is a valve, and B the seat on which it slides; C, the steam-chest, and P the passage into the cylinder.

The valve A is in form similar to the cupvalves generally used in locomotive-engines, having formed in it a cavity, a.,which is open only on the face.

The valve-seat B is elevated above the bottom of the chest G, and terminates at such distance from the passage P that when the front end of the valve A commences to uncover the said passage the cavity a in the valve will commence to overhang the edge b of the seat, as is illustrated by Fig. l, whereby double communication will be opened from the chest into the cylinder-passage I), and steam can enter past the end of the valve A, and also through its cavity a, which cavity, when the valve is wide open, overhangs equally the passage P and. the edge h of the seat, as is shown in Fig. 2, the arrows denoting the course of the steam. The mouth of the passage P, adjacent to the valve-seat, is widened, so that lwhen the valve A is wide open the aggregate width of the two passages thus afforded shall equal the general width of the passage I.

The seat B is represented as furnished with wings b b for the support of the side edges of the valve; but these maybe dispensed with.

It is evident from the foregoing description that the valve A opens or closes double the area of steam-port that it would do with the same movement if it opened communication with the port only by its end uncovering the of the valves of many steam-pumps, it opened such communication only by the cavity a overhanging the edge of the seat.

The passage I) from the valve may be short and simple in form, compared with the passages required when gridiron-valves, so termed, are employed.

The application of my invention as an eduction or exhaust valve will be readilyundersame, or that it would do if, after the manner stood by imagining the passage P open to the atmosphere and the valve A as lying in a chamber open to one end of the cylinder.

It is proper here to state that although I have described the valveseat as elevated above the surface of the chest-bottom, yet an excavation or depression of the said surface adjacent to the termination b of the seat, if sufficient to allow proper passage into the cavity of the valve, as at b and b, Fig. 5, is an equivalent construction.

Fig. 5 shows a longitudinal section of the upper partof a steam-cylinder with the chest C, valves, and seats, illustrating the application of two valves constructed, as already described, to each end of the cylinder, whereby four communications are opened into each end of the said cylinder, as is clearly shown by the position of the valves A and A', which are represented wide open.

A, A,A, and A are the four valves, connected by a rod, R, and B B B 13 their respective seats, terminating,respectively, at I), b', b, and b.

c a c ct are the cavities in the valves.

Branch passages p and p lead from the valves A and A into the main passage P, and

Vp and p lead from the valves A and A to P.

A sliding of the valves to the left from the indicated position will close the valves A and A', and a further movement in the same direction will open A and A.

Having thus fully described my invention, I disclaim as new the shape of the valve, and also an elevated seat, these being employed in locomotive and other engines; neither do I claim-the use of a cup-valve when steam is admitted to the'cylinder through t-he cup only; but

That I claim as my invention, and desire to secure by Letters Patent, is-

' The employment of a slide-valve formed as hereinb efcre sp eciied in combin ation with the described seat, when so arranged relatively to each other that an opening equal in breadth to twice the distance traversed in the same time by the valve may be made into one end of the steam-cylinder, in the manner and for the purpose aforesaid.

In testimony whereof I have hereunto set my hand this 4th day of April, 1861.

JOHN F. ALLEN.

In presence of- I'IoRAcE ANDREW, C. B. RIcHARDs. 

